Hmm, I’m not sure that’s the case here. I tried this with two different browsers (Firefox & Chrome) on two different computers, plus the native client on an Android phone, Android TV, and Android tablet, with various server settings - none of them worked.

Yep. I’m guessing it insists on transcoding the video but doesn’t have the horsepower. Plex either has a superior transcoder or detects it doesn’t need to transcode it.

For me, Plex works great on my Synology while Jellyfin is completely unusable - video payback simply crashes. Running Jellyfin on my desktop machine gets it to work, but it takes over 24 hours to scan my media library and doesn’t automatically add new media when I add new files.